Preparation

Into a large bowl sift together flour, baking powder, baking soda, and salt. Melt 5 tablespoons butter and in a small bowl whisk together with buttermilk and egg until combined. Stir butter mixture into flour mixture until smooth (batter will be thick).

Spoon batter into waffle iron, using 1 cup batter for two 4-inch-square Belgian waffles (see note, above) and spreading evenly, and cook according to manufacturer's instructions. Transfer waffles to a baking sheet and keep warm, uncovered, in middle of oven. Make more waffles in same manner (do not respray iron).

In a large heavy skillet heat remaining tablespoon butter over moderate heat until foam subsides and cook prosciutto slices until crisp and golden, about 1 minute on each side.